I have a little problem of performance ... I have a screen composed of a main grid, and above, 2 panel.
The first panel is a form that offers several search options. For example, display clients from a city, or another search option.
The 2nd panel is another grid, allowing the given sort order. For example I want my grid displays the list of city in alphabetical order, then the birthdate from youngest to oldest.
This grid being in autoHeight to reduce the place up as it change when I would like to add or delet a sort order.
When I refresh my main grid, it sends data from panel 2 (+ current page) to php and the php built with this data an SQL query (SELECT xxx WHERE yyy ORDER BY zzz LIMIT a,b).

Until then, it's so good. The two panels are collapsable, and my main grid is configured to autoHeight. The paging is 25 records.

But here is where I am coming from. I want to spend my many paging to 200 and the blow with the current state, when I go down my screen, filter and column header disparaise top.
This has the result that if for example I'm on to a random line from modify it, but i forgot what's column it is, for see the header i scroll up, and after i scroll down ! In short, absolutely not manageable. So I can not keep the grid in autoHeight ...

here's what I've tried:

for the first try, i have simply set the height of my grid (window.innerHeight-50) (50px are the height of the 2 title bar of the panel ).
That gives a result very funny, except when I open a panel, for example to initialize a filter, the bbar or main grid dive under my screen, so I am forced to close this panel for review .
So I put my listeners on the 2 panel when it open or closed I resize my grid.
It has been perfect and stops there, except that the javascript does not follow: it takes almost 8 seconds to recalculate on some computers! In other words, it is not ok.

So I tried another approach using the layout.
I have put in the "north region" my 2 panels (open) and the "center region" my main grid
this way, I get approximately the same result ...... and perf same! too slow, too bad when the user open the north!
Secondly, this solution is even worse because if I add sort orders (the grid of the 2nd panel) the last of the region so that the blow fall under the main grid (for this grid being it still autoHeight) !

Do you have an idea or solution?

Thank you for your help